(CNN) - Federal prosecutors in Tennessee have charged two men with plotting a "killing spree" against African-Americans that would have been capped with an attempt to kill Democratic presidential candidate Barack Obama.

The U.S. attorney's office in Jackson, Tennessee, said Daniel Cowart, 20, and Paul Schlesselman, 18, were self-described white supremacists who met online through a mutual friend. They have been charged with illegal possession of a sawed-off shotgun, conspiracy to rob a federally licensed gun dealer and making threats against a presidential candidate.

Cowart and Schlesselman were arrested after an aborted robbery attempt last week, prosecutors said in a statement announcing the charges. They made their initial appearances before a federal judge Monday and are scheduled for a bond hearing Thursday in Memphis.